There are some map bugs that can seriously spoil a run. During Arc 4 I had a guar stuck inside the walls of one of the arenas, and while it was possible for me to slowly damage him (once I found a sweetspot) due to the lava pond bonus thing it was a real chore since I had to kill dozens of thoat shards in the meantime. Then one of the shards also got stuck under the floor shortly before I killed the guar and as soon as the next wave spawned I was doomed since there was no way for me to interrupt it.

Another time I was kiting a marauder (the whirly one) while keeping some weak mobs from the current wave alive. They died in my AoE and the new wave spawned. I presume it had something to do with some mobs being unable to find me, but suddenly the marauder and the entire wave despawned and I lost a live without dying.

This is really frustrating stuff. Constantly losing lives to nonsense like this really brings down morale and in the end you have no buffer when you die for actual gameplay related reasons.
Generally speaking I really enjoy the Archive, but it is hard to find enough time for a serious attempt anyway. If the run is then screwed after 2+ hours due to bugs, it makes me a bit mad.